I've never been sure about where I stand on affirmations (eg, "Every day and in every way I am getting better and better") - are they flaky New Age superstition or a practical tool for changing your life? On the other hand, one technique for evoking change (from the Inner Game and from solution-focussed therapy) that I have found to be very effective is noticing key variables and scaling them (for example by asking the question "On a scale of 1 to 10, how efficiently are you working at this moment?"). Rather improbably, repeatedly getting an answer to such a question will tend to move the variable being noticed in the appropriate direction (so in this example, you will find that your efficiency increases).
Repeating an Affirmation also has the effect of focusing us on the variable we want to change. But what the scaling question adds is the ability to notice exactly how the variable is changing - and it is this concrete information that then drives an automatic learning process that leads to a change in our behaviour. Try it and see!